Climate dependence of heterotrophic soil respiration from a soil‐translocation experiment along a 3000 m tropical forest altitudinal gradient

Abstract

Summary Tropical ecosystems play a key role in the global carbon cycle, but their response to global warming is not well understood. Altitudinal gradients offer the unique possibility of undertaking in situ experimental studies of the influence of alterations in climate on the carbon (C) cycle. In a soil‐translocation experiment we took replicate soil cores at 3030 m, 1500 m, 1000 m and 200 m above sea level along an altitudinal gradient in tropical forest in Peru, and exchanged (i.e. translocated) them among these sites to observe the influence of altered climatic conditions on the decomposition of soil organic matter under natural field conditions. Soil respiration rates of the translocated soil cores and adjacent undisturbed soils were measured twice a month from April 2007 to October 2007. The temperature sensitivity of heterotrophic respiration in each core was examined using a Lloyd & Taylor function and a simple modified third‐order polynomial fit. Calculated Q10 values decreased with decreasing altitude using both mathematical functions (2.53–1.24 according to the Lloyd & Taylor function, and 2.56–0.63 using the polynomial fit). Soil organic C‐stocks increased markedly and linearly with altitude, but surprisingly the average total soil respiration rate did not vary significantly with altitude along the transect (3.98–4.31 μmol CO2 m−2 s−1). This implies an increase with elevation of absolute C allocation to below‐ground allocation.

Different effects of warming and cooling on the decomposition of soil organic matter in warm–temperate oak forests: a reciprocal translocation experiment

“…Therefore, Q 10 was mainly affected by transfer of the soils. Although different methods used to calculate Q 10 might lead to different results (Zimmermann et al 2009), Q 10 calculated by use of both the van't Hoff (the most commonly used equation) and the Lloyd and Taylor (suggested to give an unbiased estimate of Q 10 ) equations had consistent responses to the treatments in our study.…”

“…In addition, if we do not consider the direction of soil monolith transfer, both high and lowelevation soils had 44 % greater CO 2 flux when they were incubated in the low-elevation site than those incubated in the high-elevation site, indicating that the temperature difference between the two sites determined the different CO 2 flux rates. In combination with higher soil C stock at the higher-elevation site (Table 1), similar CO 2 flux rate between both soils incubated in situ implies that more C would be stored in the soil at the high-elevation site (Zimmermann et al 2009(Zimmermann et al , 2010.…”

“…Especially, reciprocal treatment (simulating climate cooling) to that of warming can strengthen the conclusions drawn from warming treatment in which temperature has a dominant effect on soil-plant processes (Hart and Perry 1999). Reciprocal soil translocation experiments have been widely used to understand the potential effects of climate change on C and nitrogen (N) cycles (Hart 2006;Hart and Perry 1999;Link et al 2003;Rey et al 2007;Zimmermann et al 2009) and soil microbial communities (Budge et al 2011).…”

Nutrient limitations to bacterial and fungal growth during cellulose decomposition in tropical forest soils

“…Further descriptions of soil properties (Quesada et al 2010;Whitaker et al 2014;Zimmermann et al 2009), climate (Rapp and Silman 2012) and aboveground productivity and floristic composition (Asner et al 2013;Feeley et al 2011;Girardin et al 2010) for these sites are reported elsewhere.…”

Climate Impacts on Soil Carbon Processes along an Elevation Gradient in the Tropical Luquillo Experimental Forest

“…However, there was no significant relation detected between soil respiration and temperature [14]. Similarly, in a study on climate dependence of heterotrophic soil respiration along a 3000-m elevation gradient in a tropical forest in Peru, Zimmermann et al (2009) also concluded that the soil respiration rate did not vary significantly along the elevation gradient with decreasing temperature, although SOC stocks increased linearly with increased elevation [17].…”